1. Field of the Invention
The present invention relates to an improved structure of umbrella, and in particular to an improved structure of umbrella, which comprises ribs and stretchers that, when the umbrella is closed, are collapsed in tangential angles to set at one side of the central shaft and the runner and are not interfered with by the central shaft and the runner so that the size of the umbrella when collapsed is reduced, the packaging material for the umbrella is reduced, and the cost is lowered down.
2. The Related Arts
A commonly known large-sized umbrella, such as a beach parasol, a garden parasol, and an advertising umbrella, has such a basic structure that is composed of a central shaft, a crown, a runner, a plurality of ribs, and a plurality of stretchers. The crown is fixed to a top end of the central shaft. The runner is fit over the central shaft to vertically slidable with respect thereto. Each of the ribs has an upper end pivoted to the crown. Each of the stretchers has an upper end pivoted to a middle portion of a respective one of the ribs and a lower end pivoted to the runner to control the vertical sliding motion of the runner along the central shaft for opening and closing a canopy.
In the conventional umbrella, if each rib of the umbrella is linear, then when the umbrella is opened, a polygonal canopy will show. If each rib is curved, then when the umbrella is open, a circular arc canopy can be formed.
The conventional umbrella that forms a circular arc canopy, although showing better aesthetics, yet suffers an apparent drawback. Since each of the ribs is curved, when the umbrella is closed, the end of each rib is blocked by the central shaft and the runner, making the middle portion of each curved rib significantly bulging out, so that the size of the umbrella is storage is increased, as shown in the attached FIG. 5. To increased storage size of the umbrella causes troubles to the user and also requires more package material and reduces the number of umbrella that can be accommodated in a unit accommodation space, so that the packaging and shipping costs of the umbrella are increased.